This project focuses on development of an effective vaccine for filovirus infection, which is an etiologic agent of highly lethal hemorrhagic fever and can be transmitted via person-to-person contact, thus posing a high threat of an epidemic outbreak. We have studied the development of VLP vaccines against virus infection, and have shown that EBOV VLPs produced in insect cells using the recombinant baculovirus expression system, which gives high VLP production yield, exhibit DC-stimulating activity and induce strong antibody responses that neutralize EBOV GP mediated virus infection, indicating that such VLPs could be safe and effective vaccines to induce protective immunity against EBOV infection. We also found that immunization with a mixture of DNA and VLP vaccines (DNA/VLP) induced higher levels of both antibody and cellular immune responses in comparison to immunization with either alone. We hypothesize that the novel DNA/VLP vaccine will elicit strong cellular and antibody responses against filovirus infection and that the employment of a new vaccine delivery technology will further augment induction of such responses, with the aim to obtain a vaccine strategy that can confer rapid and long lasting protection against filovirus infection. Specific Aim 1. To improve the immunogenicity of DNA and VLP vaccines for eliciting more potent and durable protective immunity against pan-filovirus infection. We will explore different strategies to modify filovirus DNA and VLP vaccines to enhance their immunogenicity for inducing both antibody and T cell responses as well as their production yield and will determine the immune responses that contribute to and are critical for achieving long lasting protection against filovirus infection. Specific Aim 2. To evaluate the microneedle (MN) technology for filovirus vaccine delivery. We will develop the technology to encapsulate filovirus DNA and VLP vaccines into bio-absorbable MNs and investigate the biological property, stability, and immunogenicity of encapsulated vaccines and investigate different geometrical designs and chemical formulations to further improve the MN vaccine delivery technology for achieving more efficient and reproducible vaccine encapsulation, and improved vaccine stability. Specific Aim 3. To compare the protective efficacy of different vaccine approaches and determine the immune correlates for protection against filovirus infection. We will compare immune responses induced by different vaccine formulations using both conventional intramuscular injection as well as the novel MN vaccine delivery technology and evaluate their protective efficacy against lethal filovirus challenge in small laboratory animal models as well as non-human primates and will determine the correlates of immune responses that are important for achieving long lasting protection against filovirus infection. The results will set the foundation for selection of the most effective candidate vaccine strategy for GMP production and human trials. The successful development of this vaccine strategy may also be readily applied to vaccines against other viral hemorrhagic fevers which still lack effective vaccines. Public Health Relevance: Filoviruses are etiologic agents that cause highly lethal hemorrhagic fevers and can be transmitted via person-to-person contact, thus posing a high threat to public health. We have recently demonstrated the combined benefit of two non-viral-vector based vaccine platforms and its potential for the development of an efficacious vaccine against EBOV infection. In this project we will further develop the novel DNA/VLP vaccine strategy for eliciting strong cellular and antibody responses against EBOV infection and develop a new vaccine delivery technology to further augment induction of such responses.